-LRB- CNN -RRB- -- Imagine an icy cold day , Arizona . A chilly breeze , southwest California . Snow drifting slowly from low slate clouds , Las Vegas .

Now , keep those images close at hand . You 're going to need something to help keep you cool as Mother Earth pours a big bucket of brutal heat on your head .

`` I 'm not worried as much about the people who have lived here a while , '' said Sgt. Troy Stirling , spokesman for the Lake Havasu police in that Arizona city along the California border . `` It 's more the tourists coming into the area , even from Southern California , who are n't used to this kind of heat . ''

Civic and emergency officials throughout the Southwest say that if there was ever a time to worry , this would be it . The reason is n't just the oppressive heat that plagued the region : It 's the fact it is expected to hang around , and possibly even get worse , over the next few days .

Many of the excessive heat warnings issued by the National Weather Service extend through Tuesday night , with advisories from northern California , including Sacramento , all the way to southern Arizona . Forecasters say temperatures through the weekend could rival a 2005 heat wave that killed 17 people in the Las Vegas area .

The culprit is a high pressure dome that 's blocking cooler air coming down from the Pacific Northwest , CNN meteorologist Indra Petersons explains . That system wo n't begin to break up until early next week , she said .

As a result , Phoenix residents should see a high of 118 degrees on Saturday . That 's the temperature the National Weather Service expects the thermostat will reach in Las Vegas both on Sunday and Monday . It should max out at 115 in the coming days in Palm Springs , California .

It 's not like sunset will provide much respite , as temperatures may not drop below 90 degrees in many places , even in the middle of the night .

Yet all those conditions are practically wintry compared to what 's expected in Death Valley , where temps could climb to 129 degrees .

The high temps come just a couple weeks before the 100th anniversary of what the National Weather Service calls the `` highest reliably recorded air temperature on Earth '' -- 134 degrees on July 10 , 1913 , in Death Valley 's Greenland Ranch .

It likely wo n't get that bad , but that does n't mean it wo n't be dangerous .

That 's why Stirling said authorities in Lake Havasu City are making sure every police officer on the beat has cool water or Gatorade handy , why waters at the city 's aquatic center are being chilled , and why fire stations are offering free cold water to passers-by .

Precautions are also being taken in the case of a worst-case scenario -- a power outage that knocks out air conditioning that people need to get through the intense heat .

But barring such a calamity , Stirling said , `` Most people know , ` We 're going to stay indoors . ' ''

Of course , there will be those who do n't do that -- perhaps because they have to be outside , or maybe because they 're convinced they can beat the heat .

Those fighting fires -- like a blaze that ripped through a Phoenix salvage yard Friday evening , torching vehicles , sending huge plumes of black smoke into the air and triggering several explosions -- do n't have much choice to stay inside .

In California , the so-called Mills Fire in San Bernardino County was still raging at 5:45 p.m. -LRB- 8:45 p.m. ET -RRB- Friday , having more than doubled in size to 200 acres over the course of the day , according to California 's Department of Forestry and Fire Protection .

In addition to firefighters , police pitched in by going door-to-door asking people to evacuate . But the weather was n't , and wo n't , be much help at all : Forecasts for the area call for sunny skies and temperatures topping out at 109 degrees both days this weekend .

Crissi Zito is one of those people in the heat-drenched zone who ventured outside , even if she did n't have to . Still , when she went out for a run Friday in 100-plus degree heat in Sacramento , Zito was equipped with a water bottle in her hand and the understanding in her mind that now is not the time to push your limits .

`` Listen to your body , '' she told CNN affiliate KOVR . `` If your body says , ' I do n't feel good , I do n't feel right , ' go inside , get some shade , get some water . ''

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NEW : Those fighting wildfires and other blazes must battle extreme heat as well

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Excessive heat warnings extend from northern California to Arizona and beyond

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It could reach 129 in Death Valley -- five degrees short of the all-time record

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Temperatures may not fall below 90 at night in some areas